SD cards add cheap persistent memory to your project, but the holder takes a lot of board space. A smaller option is the microSD flash format. MicroSD cards are compatible with regular SD cards, and most come with a free adapter. We looked at four holders for our mini web server. Which should you choose? Read about our experience below.
Here’s a breakdown of the microSD card holders illustrated above:
Alps SCHA1B0100 $1.27 – Can you see pins through the holes in the first holder? They ‘re hard to see, and almost inaccessible. We didn’t find this holder very useful for prototyping.
JAE ST6S008V4AR1500 $1.46 – This is another model with pins located at the front, but these are further forward for easier access. It’s still going to be a pain to solder, avoid if possible.
SparkFun PRT-00127 $3.95 – Finally, a holder with pins at the back. This is a fairly easy-to-solder part, but it’s not ideal. The soldering tabs are very small and slightly recessed under the shield. It’s also the most expensive microSD holder we’ve seen. SparkFun has a Cadsoft Eagle footprint for this part in their library. We think Molex 538-502702-0891 ($3.58) is probably very similar. We used this holder with the mini web server.
Alps SCHA2B0300 – $1.27 – The long pins along both sides of this holder are easy to solder. The holder is reversed, meaning the card inserts upside-down. Reversed holders seem weird on an all surface mount board, but they fit nicely in through-hole designs. There’s no Eagle footprint yet, but we’ll send an SCHA2B0300 to the first person who makes one; here’s the datasheet (pdf).